Manufacture of cement



15 fluoride,

so cium carbonate,

Patented Apr. 18, 1933 ROBERT ERWIN WINDECKEB, OF PAINESVILLE, OHIO nnnur'nc'runn or onmmrr No Drawing.

This invention relates to improvements in the manufacture of hydraulic cements. The invention includes improvements in the manufacture of hydraulic cement from raw materials or mixtures containing a flux, which mixtures, after clinkering, are ground with calcium or magnesium chloride to produce a hydraulic cement of high quality.

In the manufacture of hydraulic cement,

the use of fluxing agents to produce cements is well known, for example, the addition of calcium fluoride to the raw mixtures before the sintering process.

This invention includes the use of calcium or fluoride compounds, as a fluxing agent in conjunction with the use of either calcium or magnesium chloride when incorporated or ground with the clinker and the usual gypsum retarder to produce hydraulic 2c cement.

The action of calcium or magnesium chloride on a ground clinker made from raw materials containing a fluoride flux produces a hydraulic cement of high strength and qual- I 2.5 ity.

The manufacture of hydraulic cement in accordance with the invention will be illustrated by the following example:

Example I .117 12O parts by weight calor calcium oxide equivalent, clay or other silicious material, or mixtures of such materials, or of such materials and silica comprising 5.4-5.7 parts alumina, 20.2- 199 parts silica, 2.12.3 parts iron oxide and i 1-3 part-s calcium fluoride after appropriate grinding are clinkered in a kiln, for example,

at a temperature approximating 27502950 F., the clinker then ground with the usual retarder and 1-3 parts calcium or magnesium i0 chloride to produce hydraulic cement.

The raw materials subjected to the clinkering operation may be ground separately or together, wet or dry, and the ground materials may be supplied to the clinkering operation as a powder, or in agglomerated form, or as a slurry.

It is understood that the detailed example given above is intended merely to illustrate the invention, and that the invention is not limited specifically thereto. The proportions Application filed September 25, 1930. Serial No. 484,469.

of the raw materials, for instance, may be varied to conform with varying hardening properties and strengths of cement required. In the production of high early strength cements of high lime content, the combined use of fluoride fluxes inthe raw mixtures and the addition of chlorides of calcium or magnesium to the clinker during the grinding or cement blending process is advantageous.

The use of calcium fluoride, or other fluor- 5d ide flux in conjunction'with the addition of calcium or magnesium chloride during or after grinding of the clinker'oifer similar advantages in the manufacture of white hydraulic cement from raw materials of limit- 65 ed iron content. The use of such a flux and after clinkering, the incorporation of calcium or magnesium chloride toproduce hydraulic cement is advantageous in a raw material mixture such as the following examples Example H.120 parts by weight of cal cium carbonate, or calcium oxide equivalent, kaolin or clay or other, silicious material, or mixtures of such materials, or of such materials and silica comprising'8.0 parts alumina '2'; and 25.5 parts silica'and 13 jpartscalcium fluoride, after appropriate grinding 7 are clinkered in a conventional rotary kiln, for example, at a temperature approximating 27002900 F. The iron content of the mixa ture subjected to the clinkering operation is limited not to exceed about 0.4% of iron, com puted as iron oxide, the clinker then ground with the retarder and 1-3 parts calcium or magnesium'chloride to produce hydraulic cement. 7 1 I Emample I I I .-120 parts by weight of calcium carbonate, or calcium oxide equiv alent, kaolin or clay or other silicious material, or, mixtures of such materials, or of such materials and silica, comprising 9.3 parts alumina and 21.9 parts silica and 13 parts calcium fluoride, after appropriate grinding are clinkered in a conventional rotary kiln, for example, at a temperature approximating 27002900 F. The-iron content of the mixture subjected to the clinkering operation is limited not to exceed about 0.4% of iron, computed as ironoxide,-the

clinker then ground with the retarder and 100 ple, at a temperature approximating 2750- 1-3 parts calcium or magnesium chloride to produce hydraulic cement.

Example IV.12O parts by Weight of calcium carbonate, or calcium oxide equivalent, kaolin or clay or other silicious material, or mixtures of such materials, or of such materials and silica-comprising 6.5 parts alumina and 23.3 parts silica and 1-3' parts calcium fluoride, after appropriate grinding are clinkered in a conventional rotary kiln, for exam- 2950 F. The iron content of the mixture subjected to the clinkering operation is limited not to exceed about 0.4% of iron, computed as iron oxide, the with the retarder and'l-3 parts calcium or magnesium chloride to produce hydraulic cement.

It is understood that the detailed examples given above are intended merely to illustrate the invention, and that the invention is not limited specifically thereto. The addi tion of calcium fluoride, or other alkaline earth metal fluorides, not only tends to decrease the more advantageous range of clinkering temperatures but also assists in the production of cements developing high early strengths inconjunction with good ultimate strengths. The amountof calcium fluoride or other fluoride flux may be varied, for example, from to 5%.v In general, 1.5% to 2.5%, based on the Weight ofthe clinker produced, is an advantageous proportion. The flux may be added to the raw material mixture at any time beforeor during the clinkering operation.

clinker then ground group consisting of calcium and magnesium chlorides in the cement produced by grinding the clinker.

2. In the manufacture of hydraulic cement, the improvement comprising clinkering a mixture containing calcium carbonate, alumina, silica and a fluoride flux and incorporating a chloride selected from the group consisting of calcium and magnesium chlorides in the cement produced by grinding the clinker.

3. In the manufacture of White hydraulic cement, the improvement comprising clinkering a mixture containing calcium carbonate, alumina, silica and a fluoride flux, the iron content of- Which clinker produced will contain less than about 0.4% iron, computed as iron oxide, and incorporating a chloride selected from the group consisting of calcium and magnesium chlorides in the cement produced by grinding the clinker. I

I n testimony whereof I aiiix my signature. ROBERT ERWVIN WIN DECKER.

The development of high early strengthof cement produced by the addition of a fluoride flux to the raW material as just described and the addition. of. calcium or magnesium chloride to the clinker-is not limited, according to the invention, to the proportions given above. The calcium or magnesium chloride may be varied, for example, from to 5%, in general 1.5% to 2.5%, by eight of the clinker, and the calcium or magnesium chloride may be added to the clinker before grinding or during grinding-or blending or at any time, including thetime of mixing ofthe'cement With stone, sand or other materials with Water to mould or produce solid objects; The

chloride may be added With thesuitable amount of gypsum retarder.

In makinghydraulic cement acording to thisinvention, the clinkeringoperation may becarried out in any type-of furnace or kiln found suitable for the operatiomthe invention not being limited to the use of a rotary is limited so that the 

